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I've installed my wideband O2 "gauge" and seeing some potentially bad behavior that I don't know enough to know where to start. I tried to capture it in the video below.

The car generally runs good and throttle response feels pretty good. It is much better since I changed the vacuum secondary screw to come in earlier.

Engine is mildly modified with unknown compression pop-up pistons, 4V open chamber heads, Blue Thunder intake, big bore stainless headers.
Carb is a Quick Fuel HR-780-VS. I would be amazed if it isn't exactly as it was when it came out of the box as far as jetting.
Specs here:

Primary Jet Size:
Primary Power Valve (Hg):
6.5 Hg
Primary Discharge Nozzle Size (in.):
0.031 in.
Secondary Jet Size:

I get 15-16 inches of vacuum at idle.
Hot idle is a bit fat at 12.6 or so.

Thanks in advance and Happy New Year!

Last edited by jmardy
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If you are idling at a fuel air ratio of 12.6:1, then that is way too rich. You can adjust your carb primary idle adjustment screws and get that ratio up, but I am not sure if you can get it up to around the 13.7:1 area. You should confirm your carb jet sizes to start with. I will PM you with some better information on what I have done with my car.

The aftermarket fuel injection systems just keep getting better! With the on board monitors that they have, you can see everything that is going on with the system. Altitude changes are not an issue and cold starts are just smooth. I am feeding about 600 horsepower and can get 18 to 20 mph on the highway if I just drive the speed limit and don't get crazy. Just try a simple throttle body system to start with and you will get the idea.

I know this is now an old post but I thought I'd update how I resolved this in case someone has a similar issue in the future.
I went up to a size 40 squirter and adjusted the vacuum secondary speed screw almost all the way in/later. The lean peak was from too much air/not enough fuel when going toward WOT. These two things remedied it. Car is running great now. Thanks for all the help, as always.

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